Diabetic cardiomyopathy is associated with suppressed autophagy and augmented inflammation in the heart. The effects of Tax1 binding protein 1 (TAX1BP1) on both autophagy and inflammation suggest that it may participate in the progression of diabetic cardiomyopathy. Mice were injected with streptozotocin (STZ) to induce experimental diabetes. An adenovirus system was used to induce heart specific TAX1BP1 overexpression 12 weeks after STZ injection. TAX1BP1 expression was significantly decreased in STZ-induced diabetic mouse hearts. TAX1BP1 overexpression in the heart alleviated cardiac hypertrophy and fibrosis, attenuated inflammation, oxidative stress, and apoptosis, and improved cardiac function in STZ-induced diabetic mice. Diabetic mice exhibited decreased autophagy. By contrast, increased autophagy was observed in diabetic mice overexpressing TAX1BP1. TAX1BP1 overexpression promoted autophagic flux, as demonstrated by increased LC3-RFP fluorescence in vitro. Furthermore, the autophagy inhibitor 3-MA abolished the protective effects of TAX1BP1 in vivo. Interestingly, we found that TAX1BP1 increased autophagy via the activation of a non-canonical NF-κB signaling pathway. Conversely, RelB knockdown disrupted the protective effects of TAX1BP1 in cardiomyocytes. TAX1BP1 thus restores the decreased autophagy level, leading to decreased inflammatory responses and oxidative stress and reduced apoptosis in cardiomyocytes.

Whether aucubin could protect myocardial infarction- (MI-) induced cardiac remodeling is not clear. In this study, in a mouse model, cardiac remodeling was induced by left anterior descending coronary artery ligation surgery. Mice were intraperitoneally injected with aucubin (10 mg/kg) 3 days post-MI. Two weeks post-MI, mice in the aucubin treatment group showed decreased mortality, decreased infarct size, and improved cardiac function. Aucubin also decreased cardiac remodeling post-MI. Consistently, aucubin protected cardiomyocytes against hypoxic injury in vitro. Mechanistically, we found that aucubin inhibited the ASK1/JNK signaling. These effects were abolished by the JNK activator. Moreover, we found that the oxidative stress was attenuated in both in vivo aucubin-treated mice heart and in vitro-treated cardiomyocytes, which caused decreased thioredoxin (Trx) consumption, leading to ASK1 forming the inactive complex with Trx. Aucubin increased nNOS-derived NO production in vivo and vitro. The protective effects of aucubin were reversed by the NOS inhibitors L-NAME and L-VINO in vitro. Furthermore, nNOS knockout mice also reversed the protective effects of aucubin on cardiac remodeling. Taken together, aucubin protects against cardiac remodeling post-MI through activation of the nNOS/NO pathway, which subsequently attenuates the ROS production, increases Trx preservation, and leads to inhibition of the ASK1/JNK pathway.

Aucubin (AUB), which is extracted from Eucommia ulmoides Oliver seeds, has been found to possess anti-inflammatory and antiapoptotic properties. Recent studies have indicated that inflammation, oxidative stress, and apoptosis are involved in the pathophysiology of lipopolysaccharide (LPS)-induced cardiac dysfunction. Our study aimed to investigate the effect of AUB on LPS-induced acute cardiac injury. Male C57BL/6 mice were injected with LPS (one 6 mg/kg injection) to induce cardiac dysfunction without or with AUB pretreatment (20 or 80 mg/kg per day) for 1 week. We found that AUB ameliorated cardiac dysfunction, inflammation, oxidative stress, and apoptosis induced by LPS stimulation. Mechanistically, AUB inhibited LPSinduced oxidative stress by decreasing reactive oxygen species and thioredoxin interaction protein (TXNIP) levels. Moreover, AUB suppressed LPS-induced inflammation and apoptosis by reducing nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3)/apoptosisassociated speck-like protein containing a caspase recruitment domain (ASC)/caspase-1 inflammasome formation. Overexpression of NLRP3 in cardiomyocytes attenuated the protective effects of AUB. Interestingly, NLRP3 deficiency ameliorated cardiac function and reduced the inflammatory response and oxidative stress after LPS insult in mice, whereas AUB could not further prevent LPS-induced cardiac dysfunction in NLRP3deficient mice. In summary, AUB exerts a protective effect against LPS-induced inflammation, oxidative stress, and apoptosis in vivo and in vitro by regulating the TXNIP pathway and inactivating the NLRP3/ASC/caspase-1 inflammasome. Hence, AUB may be a promising agent against LPS-induced cardiac dysfunction. SIGNIFICANCE STATEMENT Aucubin exerts a protective effect against lipopolysaccharideinduced cardiac dysfunction by regulating nucleotide-binding oligomerization domain-like receptor family pyrin domaincontaining 3 inflammasome.